/*
** $Id: loadlib.c,v 1.51 2005/12/29 15:32:11 roberto Exp $
** Dynamic library loader for Lua
** See Copyright Notice in lua.h
**
** This module contains an implementation of loadlib for Unix systems
** that have dlfcn, an implementation for Darwin (Mac OS X), an
** implementation for Windows, and a stub for other systems.
*/

#include <stdlib.h>
#include <string.h>


#define loadlib_c
#define LUA_LIB

#include "lauxlib.h"
#include "lobject.h"
#include "lua.h"
#include "lualib.h"


/* environment variables that hold the search path for packages */
#define LUA_PATH	"LUA_PATH"
#define LUA_CPATH	"LUA_CPATH"

/* prefix for open functions in C libraries */
#define LUA_POF		"luaopen_"

/* separator for open functions in C libraries */
#define LUA_OFSEP	"_"


#define LIBPREFIX	"LOADLIB: "

#define POF		LUA_POF
#define LIB_FAIL	"open"


/* error codes for ll_loadfunc */
#define ERRLIB		1
#define ERRFUNC		2

#define setprogdir(L)		((void)0)


static void		ll_unloadlib (void *lib);
static void *	ll_load (lua_State *L, const char *path);
static			lua_CFunction ll_sym (lua_State *L, void *lib, const char *sym);



#if defined(LUA_DL_DLOPEN)
/*
** {========================================================================
** This is an implementation of loadlib based on the dlfcn interface.
** The dlfcn interface is available in Linux, SunOS, Solaris, IRIX, FreeBSD,
** NetBSD, AIX 4.2, HPUX 11, and  probably most other Unix flavors, at least
** as an emulation layer on top of native functions.
** =========================================================================
*/

#include <dlfcn.h>

static void ll_unloadlib (void *lib) {
	dlclose(lib);
}


static void *ll_load (lua_State *L, const char *path) {
	void *lib = dlopen(path, RTLD_NOW);
	if (lib == NULL) lua_pushstring(L, dlerror());
	return lib;
}


static lua_CFunction ll_sym (lua_State *L, void *lib, const char *sym) {
	lua_CFunction f = (lua_CFunction)dlsym(lib, sym);
	if (f == NULL) lua_pushstring(L, dlerror());
	return f;
}

/* }====================================================== */



#elif defined(LUA_DL_DLL)
/*
** {======================================================================
** This is an implementation of loadlib for Windows using native functions.
** =======================================================================
*/

#include <windows.h>


#undef setprogdir

static void 
setprogdir (lua_State *L)
{
	char buff[MAX_PATH + 1];
	char *lb;
	DWORD nsize = sizeof(buff)/sizeof(char);
	DWORD n = GetModuleFileName(NULL, buff, nsize);
	if (n == 0 || n == nsize || (lb = strrchr(buff, '\\')) == NULL)
		luaL_error(L, "unable to get ModuleFileName");
	else
	{
		*lb = '\0';
		luaL_gsub(L, lua_tostring(L, -1), LUA_EXECDIR, buff);
		lua_remove(L, -2);  /* remove original string */
	}
}


static void 
pusherror (lua_State *L)
{
	int error = GetLastError();
	char buffer[128];
	if (FormatMessage(FORMAT_MESSAGE_IGNORE_INSERTS | FORMAT_MESSAGE_FROM_SYSTEM, NULL, error, 0, buffer, sizeof(buffer), NULL))
		lua_pushstring(L, buffer);
	else
		lua_pushfstring(L, "system error %d\n", error);
}

static void
ll_unloadlib (void *lib)
{
	FreeLibrary((HINSTANCE)lib);
}


static void *
ll_load (lua_State *L, const char *path) 
{
	HINSTANCE lib = LoadLibrary(path);
	if (lib == NULL)
		pusherror(L);

	return lib;
}


static 
lua_CFunction ll_sym (lua_State *L, void *lib, const char *sym) 
{
	lua_CFunction f = (lua_CFunction)GetProcAddress((HINSTANCE)lib, sym);
	if (f == NULL)
		pusherror(L);

	return f;
}

/* }====================================================== */



#elif defined(LUA_DL_DYLD)
/*
** {======================================================================
** Native Mac OS X / Darwin Implementation
** =======================================================================
*/

#include <mach-o/dyld.h>


/* Mac appends a `_' before C function names */
#undef POF
#define POF	"_" LUA_POF


static void pusherror (lua_State *L) {
	const char *err_str;
	const char *err_file;
	NSLinkEditErrors err;
	int err_num;
	NSLinkEditError(&err, &err_num, &err_file, &err_str);
	lua_pushstring(L, err_str);
}


static const char *errorfromcode (NSObjectFileImageReturnCode ret) {
	switch (ret) {
	case NSObjectFileImageInappropriateFile:
		return "file is not a bundle";
	case NSObjectFileImageArch:
		return "library is for wrong CPU type";
	case NSObjectFileImageFormat:
		return "bad format";
	case NSObjectFileImageAccess:
		return "cannot access file";
	case NSObjectFileImageFailure:
	default:
		return "unable to load library";
	}
}


static void ll_unloadlib (void *lib) {
	NSUnLinkModule((NSModule)lib, NSUNLINKMODULE_OPTION_RESET_LAZY_REFERENCES);
}


static void *ll_load (lua_State *L, const char *path) {
	NSObjectFileImage img;
	NSObjectFileImageReturnCode ret;
	/* this would be a rare case, but prevents crashing if it happens */
	if(!_dyld_present()) {
		lua_pushliteral(L, "dyld not present");
		return NULL;
	}
	ret = NSCreateObjectFileImageFromFile(path, &img);
	if (ret == NSObjectFileImageSuccess) {
		NSModule mod = NSLinkModule(img, path, NSLINKMODULE_OPTION_PRIVATE |
			NSLINKMODULE_OPTION_RETURN_ON_ERROR);
		NSDestroyObjectFileImage(img);
		if (mod == NULL) pusherror(L);
		return mod;
	}
	lua_pushstring(L, errorfromcode(ret));
	return NULL;
}


static lua_CFunction ll_sym (lua_State *L, void *lib, const char *sym) {
	NSSymbol nss = NSLookupSymbolInModule((NSModule)lib, sym);
	if (nss == NULL) {
		lua_pushfstring(L, "symbol " LUA_QS " not found", sym);
		return NULL;
	}
	return (lua_CFunction)NSAddressOfSymbol(nss);
}

/* }====================================================== */



#else
/*
** {======================================================
** Fallback for other systems
** =======================================================
*/

#undef LIB_FAIL
#define LIB_FAIL	"absent"


#define DLMSG	"dynamic libraries not enabled; check your Lua installation"


static void 
ll_unloadlib (void *lib) 
{
	(void)lib;  /* to avoid warnings */
}


static void *
ll_load (lua_State *L, const char *path) 
{
	(void)path;  /* to avoid warnings */
	lua_pushliteral(L, DLMSG);
	return NULL;
}


static 
lua_CFunction ll_sym (lua_State *L, void *lib, const char *sym) {
	(void)lib; (void)sym;  /* to avoid warnings */
	lua_pushliteral(L, DLMSG);
	return NULL;
}

/* }====================================================== */
#endif



static void **
ll_register (lua_State *L, const char *path)
{
	void **plib;
	lua_pushfstring(L, "%s%s", LIBPREFIX, path);
	lua_gettable(L, LUA_REGISTRYINDEX);  /* check library in registry? */
	if (!lua_isnil(L, -1))  /* is there an entry? */
		plib = (void **)lua_touserdata(L, -1);
	else	/* no entry yet; create one */
	{  
		lua_pop(L, 1);
		plib = (void **)lua_newuserdata(L, sizeof(const void *));
		*plib = NULL;
		luaL_getmetatable(L, "_LOADLIB");
		lua_setmetatable(L, -2);
		lua_pushfstring(L, "%s%s", LIBPREFIX, path);
		lua_pushvalue(L, -2);
		lua_settable(L, LUA_REGISTRYINDEX);
	}

	return plib;
}


/*
** __gc tag method: calls library's `ll_unloadlib' function with the lib
** handle
*/
static int 
gctm (lua_State *L)
{
	void **lib = (void **)luaL_checkudata(L, 1, "_LOADLIB");
	if (*lib)
		ll_unloadlib(*lib);
	*lib = NULL;  /* mark library as closed */

	return 0;
}


static int
ll_loadfunc (lua_State *L, const char *path, const char *sym)
{
	void **reg = ll_register(L, path);
	if (*reg == NULL) *reg = ll_load(L, path);
	if (*reg == NULL)
		return ERRLIB;  /* unable to load library */
	else 
	{
		lua_CFunction f = ll_sym(L, *reg, sym);
		if (f == NULL)
			return ERRFUNC;  /* unable to find function */
		lua_pushcfunction(L, f);

		return 0;  /* return function */
	}
}


static int 
ll_loadlib (lua_State *L) 
{
	const char *path = luaL_checkstring(L, 1);
	const char *init = luaL_checkstring(L, 2);
	int stat = ll_loadfunc(L, path, init);
	if (stat == 0)  /* no errors? */
		return 1;  /* return the loaded function */
	else	/* error; error message is on stack top */
	{  
		lua_pushnil(L);
		lua_insert(L, -2);
		lua_pushstring(L, (stat == ERRLIB) ?  LIB_FAIL : "init");

		return 3;  /* return nil, error message, and where */
	}
}



/*
** {======================================================
** 'require' function
** =======================================================
*/


static int 
readable (const char *filename) 
{
	FILE *f = fopen(filename, "r");  /* try to open file */
	if (f == NULL) return 0;  /* open failed */
	fclose(f);

	return 1;
}


static const char *
pushnexttemplate (lua_State *L, const char *path) 
{
	const char *l;
	while (*path == *LUA_PATHSEP) path++;  /* skip separators */
	if (*path == '\0') return NULL;  /* no more templates */
	l = strchr(path, *LUA_PATHSEP);  /* find next separator */
	if (l == NULL) l = path + strlen(path);
	lua_pushlstring(L, path, l - path);  /* template */

	return l;
}


static const char *
findfile (lua_State *L, const char *name, const char *pname)
{
	const char *path;
	name = luaL_gsub(L, name, ".", LUA_DIRSEP);
	lua_getfield(L, LUA_ENVIRONINDEX, pname);
	path = lua_tostring(L, -1);
	if (path == NULL)
		luaL_error(L, LUA_QL("package.%s") " must be a string", pname);
	lua_pushstring(L, "");  /* error accumulator */
	while ((path = pushnexttemplate(L, path)) != NULL)
	{
		const char *filename;
		filename = luaL_gsub(L, lua_tostring(L, -1), LUA_PATH_MARK, name);
		if (readable(filename))  /* does file exist and is readable? */
			return filename;  /* return that file name */
		lua_pop(L, 2);  /* remove path template and file name */ 
		luaO_pushfstring(L, "\n\tno file " LUA_QS, filename);
		lua_concat(L, 2);
	}
	return NULL;  /* not found */
}


static void 
loaderror (lua_State *L, const char *filename)
{
	luaL_error(L, "error loading module " LUA_QS " from file " LUA_QS ":\n\t%s",
		lua_tostring(L, 1), filename, lua_tostring(L, -1));
}


static int 
loader_Lua (lua_State *L)
{
	const char *filename;
	const char *name = luaL_checkstring(L, 1);
	filename = findfile(L, name, "path");
	if (filename == NULL) return 1;  /* library not found in this path */
	if (luaL_loadfile(L, filename) != 0)
		loaderror(L, filename);

	return 1;  /* library loaded successfully */
}


static const char *
mkfuncname (lua_State *L, const char *modname) 
{
	const char *funcname;
	const char *mark = strchr(modname, *LUA_IGMARK);
	if (mark) modname = mark + 1;
	funcname = luaL_gsub(L, modname, ".", LUA_OFSEP);
	funcname = lua_pushfstring(L, POF"%s", funcname);
	lua_remove(L, -2);  /* remove 'gsub' result */

	return funcname;
}


static int 
loader_C (lua_State *L)
{
	const char *funcname;
	const char *name = luaL_checkstring(L, 1);
	const char *filename = findfile(L, name, "cpath");
	if (filename == NULL) return 1;  /* library not found in this path */
	funcname = mkfuncname(L, name);
	if (ll_loadfunc(L, filename, funcname) != 0)
		loaderror(L, filename);

	return 1;  /* library loaded successfully */
}


static int 
loader_Croot (lua_State *L)
{
	const char *funcname;
	const char *filename;
	const char *name = luaL_checkstring(L, 1);
	const char *p = strchr(name, '.');
	int stat;
	if (p == NULL) return 0;  /* is root */
	lua_pushlstring(L, name, p - name);
	filename = findfile(L, lua_tostring(L, -1), "cpath");
	if (filename == NULL) return 1;  /* root not found */
	funcname = mkfuncname(L, name);
	if ((stat = ll_loadfunc(L, filename, funcname)) != 0) 
	{
		if (stat != ERRFUNC) loaderror(L, filename);  /* real error */
		luaO_pushfstring(L, "\n\tno module " LUA_QS " in file " LUA_QS, name, filename);
		return 1;  /* function not found */
	}

	return 1;
}


static int
loader_preload (lua_State *L) 
{
	const char *name = luaL_checkstring(L, 1);
	lua_getfield(L, LUA_ENVIRONINDEX, "preload");
	if (!lua_istable(L, -1))
		luaL_error(L, LUA_QL("package.preload") " must be a table");
	lua_getfield(L, -1, name);
	if (lua_isnil(L, -1))  /* not found? */
		luaO_pushfstring(L, "\n\tno field package.preload['%s']", name);

	return 1;
}


static const int sentinel_ = 0;
#define sentinel	((void *)&sentinel_)


static int
ll_require (lua_State *L)
{
	const char *name = luaL_checkstring(L, 1);
	int i;
	lua_settop(L, 1);  /* _LOADED table will be at index 2 */
	lua_getfield(L, LUA_REGISTRYINDEX, "_LOADED");
	lua_getfield(L, 2, name);
	if (lua_toboolean(L, -1))	 /* is it there? */
	{ 
		if (lua_touserdata(L, -1) == sentinel)  /* check loops */
			luaL_error(L, "loop or previous error loading module " LUA_QS, name);

		return 1;  /* package is already loaded */
	}
	/* else must load it; iterate over available loaders */
	lua_getfield(L, LUA_ENVIRONINDEX, "loaders");
	if (!lua_istable(L, -1))
		luaL_error(L, LUA_QL("package.loaders") " must be a table");
	lua_pushstring(L, "");  /* error message accumulator */

	for (i=1; ; i++) 
	{
		lua_rawgeti(L, -2, i);  /* get a loader */
		if (lua_isnil(L, -1))
			luaL_error(L, "module " LUA_QS " not found:%s",
			name, lua_tostring(L, -2));
		lua_pushstring(L, name);
		lua_call(L, 1, 1);  /* call it */
		if (lua_isfunction(L, -1))  /* did it find module? */
			break;  /* module loaded successfully */
		else if (lua_isstring(L, -1))  /* loader returned error message? */
			lua_concat(L, 2);  /* accumulate it */
		else
			lua_pop(L, 1);
	}
	lua_pushlightuserdata(L, sentinel);
	lua_setfield(L, 2, name);  /* _LOADED[name] = sentinel */
	lua_pushstring(L, name);  /* pass name as argument to module */
	lua_call(L, 1, 1);  /* run loaded module */
	if (!lua_isnil(L, -1))  /* non-nil return? */
		lua_setfield(L, 2, name);  /* _LOADED[name] = returned value */
	lua_getfield(L, 2, name);
	if (lua_touserdata(L, -1) == sentinel)	 /* module did not set a value? */
	{  
		lua_pushboolean(L, 1);  /* use true as result */
		lua_pushvalue(L, -1);  /* extra copy to be returned */
		lua_setfield(L, 2, name);  /* _LOADED[name] = true */
	}
	return 1;
}

/* }====================================================== */



/*
** {======================================================
** 'module' function
** =======================================================
*/


static void setfenv (lua_State *L)
{
	lua_Debug ar;
	lua_getstack(L, 1, &ar);
	lua_getinfo(L, "f", &ar);
	lua_pushvalue(L, -2);
	lua_setfenv(L, -2);
	lua_pop(L, 1);
}


static void
dooptions (lua_State *L, int n)
{
	int i;
	for (i = 2; i <= n; i++)
	{
		lua_pushvalue(L, i);  /* get option (a function) */
		lua_pushvalue(L, -2);  /* module */
		lua_call(L, 1, 0);
	}
}


static void
modinit (lua_State *L, const char *modname)
{
	const char *dot;
	lua_pushvalue(L, -1);
	lua_setfield(L, -2, "_M");  /* module._M = module */
	lua_pushstring(L, modname);
	lua_setfield(L, -2, "_NAME");
	dot = strrchr(modname, '.');  /* look for last dot in module name */
	if (dot == NULL)
		dot = modname;
	else 
		dot++;
	/* set _PACKAGE as package name (full module name minus last part) */
	lua_pushlstring(L, modname, dot - modname);
	lua_setfield(L, -2, "_PACKAGE");
}


static int 
ll_module (lua_State *L)
{
	const char *modname = luaL_checkstring(L, 1);
	int loaded = lua_gettop(L) + 1;  /* index of _LOADED table */
	lua_getfield(L, LUA_REGISTRYINDEX, "_LOADED");
	lua_getfield(L, loaded, modname);  /* get _LOADED[modname] */
	if (!lua_istable(L, -1))	 /* not found? */
	{ 
		lua_pop(L, 1);  /* remove previous result */
		/* try global variable (and create one if it does not exist) */
		if (luaL_findtable(L, LUA_GLOBALSINDEX, modname, 1) != NULL)
			return luaL_error(L, "name conflict for module " LUA_QS, modname);
		lua_pushvalue(L, -1);
		lua_setfield(L, loaded, modname);  /* _LOADED[modname] = new table */
	}
	/* check whether table already has a _NAME field */
	lua_getfield(L, -1, "_NAME");
	if (!lua_isnil(L, -1))  /* is table an initialized module? */
		lua_pop(L, 1);
	else	 /* no; initialize it */
	{ 
		lua_pop(L, 1);
		modinit(L, modname);
	}
	lua_pushvalue(L, -1);
	setfenv(L);
	dooptions(L, loaded - 1);

	return 0;
}


static int 
ll_seeall (lua_State *L) 
{
	luaL_checktype(L, 1, LUA_TTABLE);
	if (!lua_getmetatable(L, 1)) 
	{
		lua_createtable(L, 0, 1); /* create new metatable */
		lua_pushvalue(L, -1);
		lua_setmetatable(L, 1);
	}
	lua_pushvalue(L, LUA_GLOBALSINDEX);
	lua_setfield(L, -2, "__index");  /* mt.__index = _G */

	return 0;
}


/* }====================================================== */



/* auxiliary mark (for internal use) */
#define AUXMARK		"\1"

static void 
setpath (lua_State *L, const char *fieldname, const char *envname, const char *def) 
{
	const char *path = getenv(envname);
	if (path == NULL)  /* no environment variable? */
		lua_pushstring(L, def);  /* use default */
	else
	{
		/* replace ";;" by ";AUXMARK;" and then AUXMARK by default path */
		path = luaL_gsub(L, path, LUA_PATHSEP LUA_PATHSEP,
			LUA_PATHSEP AUXMARK LUA_PATHSEP);
		luaL_gsub(L, path, AUXMARK, def);
		lua_remove(L, -2);
	}
	setprogdir(L);
	lua_setfield(L, -2, fieldname);
}


static const luaL_Reg pk_funcs[] =
{
	{"loadlib",		ll_loadlib},
	{"seeall",		ll_seeall},
	{NULL,			NULL}
};


static const luaL_Reg ll_funcs[] = 
{
	{"module",		ll_module},
	{"require",		ll_require},
	{NULL,			NULL}
};


static const lua_CFunction loaders[] =
{
	loader_preload,
	loader_Lua, 
	loader_C, 
	loader_Croot,
	NULL
};


LUALIB_API int
luaopen_package (lua_State *L)
{
	int i;
	/* create new type _LOADLIB */
	luaL_newmetatable(L, "_LOADLIB");
	lua_pushcfunction(L, gctm);
	lua_setfield(L, -2, "__gc");
	/* create `package' table */
	luaL_register(L, LUA_LOADLIBNAME, pk_funcs);
#if defined(LUA_COMPAT_LOADLIB) 
	lua_getfield(L, -1, "loadlib");
	lua_setfield(L, LUA_GLOBALSINDEX, "loadlib");
#endif
	lua_pushvalue(L, -1);
	lua_replace(L, LUA_ENVIRONINDEX);
	/* create `loaders' table */
	lua_createtable(L, 0, sizeof(loaders)/sizeof(loaders[0]) - 1);
	/* fill it with pre-defined loaders */
	for (i=0; loaders[i] != NULL; i++)
	{
		lua_pushcfunction(L, loaders[i]);
		lua_rawseti(L, -2, i+1);
	}
	lua_setfield(L, -2, "loaders");  /* put it in field `loaders' */
	setpath(L, "path", LUA_PATH, LUA_PATH_DEFAULT);  /* set field `path' */
	setpath(L, "cpath", LUA_CPATH, LUA_CPATH_DEFAULT); /* set field `cpath' */
	/* store config information */
	lua_pushstring(L, LUA_DIRSEP "\n" LUA_PATHSEP "\n" LUA_PATH_MARK "\n" LUA_EXECDIR "\n" LUA_IGMARK);
	lua_setfield(L, -2, "config");
	/* set field `loaded' */
	luaL_findtable(L, LUA_REGISTRYINDEX, "_LOADED", 2);
	lua_setfield(L, -2, "loaded");
	/* set field `preload' */
	lua_newtable(L);
	lua_setfield(L, -2, "preload");
	lua_pushvalue(L, LUA_GLOBALSINDEX);
	luaL_register(L, NULL, ll_funcs);  /* open lib into global table */
	lua_pop(L, 1);

	return 1;  /* return 'package' table */
}

